Muffler with rotary gas flow

ABSTRACT

A muffler has a gas flow path with inlet and outlet louver patches containing louvers that are directed circumferentially of the path but in opposite directions.

United States Patent [191 Haren MUFFLER WITH ROTARY GAS FLOW [75] Inventor: Ralph J. Haren, Jackson, Mich. [731 Assignee: Tenneco Inc., Racine, Wis.

[22] Filed: Nov. 8, 1972 [2]] Appl. No.: 304,770

[52] US. Cl. 181/55, 181/36 B [51] Int. Cl. FOln 1/08 [58] Field of Search 181/41, 55, 49, 36 B [56] References Cited UNITED STATES PATENTS 2,047,443 7/1936 Starkweather 181/41 5] Jan.7, 1975 11/1937 Heath 181/36 B 3/1939 Starkweather 181/55 Primary ExaminerRichard B. Wilkinson Assistant Examiner-Vit W. Miska Attorney, Agent, or Firm-Harness, Dickey & Pierce [57] ABSTRACT A muffler has a gas flow path with inlet and outlet louver patches containing louvers that are directed circumferentially of the path but in opposite directions.

6 Claims, 7 Drawing Figures PATENTEB JAN 7 I975 sum 1 or 2 1 MUFFLER WITH ROTARY GAS FLOW BRIEF SUMMARY OF THE INVENTION It is the purpose of this invention to improve the sound attenuation of a muffler of the type used in the exhaust systems of internal combustion engines.

The invention accomplishes this by means of inlet and outlet louver patches in the path of gas flow in which the louvers are disposed so that the gas rotates or swirls in only one direction in flowing through them.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross section through one form of muffler embodying the invention;

FIG. 2 is a cross section along the line 2-2 of FIG.

FIG. 3 is a cross section along the line 33 of FIG.

FIG. 4 is a broken away portion of a longitudinal sec tion similar to that of FIG. 1 wherein the cneter plug is removed and a neckdown section utilized to force gas flow through the louver patches;

FIG. 5 is a longitudinal cross section through a modified form of the invention;

FIG. 6 is a cross section along the line 6-6 of FIG. 5; and

FIG. 7 is a cross section along the line 7-7 of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION The muffler 1 of FIGS. 1 4 has an outer shell 3 which is reduced in diameter at each end to provide an inlet bushing 5 and an outlet bushing 7 which are slotted at 9 to permit tight clamping of the muffler to exhaust and tailpipe conduits (not shown). The shell 3 may have coaxial enlargements 11 and 13 adjacent the inlet and outlet bushings to serve as support surfaces for the opposite ends of a flow tube 15 that has open ends to communicate with the bushings 5 and 7. The center section of the tube 15 contains flow obstruction means to prevent or restrict straight through gas flow as illustrated, respectively, by the fixed imperforate partition or plug 17 of FIG. 1 or the necked down area 19 (FIG. 4) as provided by pinches 21 in the wall of tube 15. On the upstream side of the partition 17 (or area 19) the tube has a louver patch 23 that serves as an inlet opening for gas flow into the chamber 25 from the tube. On the downstream side of the partition 17 (or area 19) the tube has a louver patch 27 that serves as an outlet for gas flow from chamber 25 into the tube. The total open area of each patch of louvers is preferably substantially the same, though in some designs it may be desirable to make the inlet patch slightly larger. The means 17 or 21 forces all or some of the gas, respectively, to flow through chamber 25 in passing through the muffler.

The louvers 31 in each of the patches 23 and 27 may be of conventional shape and arrangement and are preferably in accord with the teachings of US. Pat. No. 1,949,074 of Earl G. Gunn. Thus, they are preferably equally angularly spaced in uniformly longitudinally separated circumferential rows or hands extending all the way around the tube with the louvers in each row staggered or offset with respect to louvers in the adjacent row. In accordance with this invention, the louvers in the patch 23 face or open in one tangential direction (e.g., counterclockwise) as seen in FIG. 2 while the louvers in the other patch 27 face are open in the opposite tangential direction (e.g., clockwise) as seen in FIG. 3. Thus, gas leaving inlet patch 23 to enter chamber 25 will be moving or swirling in the direciton of the counterclockwise arrow 33 as it also moves longitudinally down the length of chamber 25. Since the outlet louvers in patch 27 open in a clockwise direction, the counterclockwise rotating body of gas can easily enter them, as shown by arrow 33 in FIG. 3, so that a minimum back pressure condition is provided for gas flow through two sets of louvers. Furthermore, the desired acoustic attenuation provided by gas flow through louvers is obtained and, in fact, improved somewhat over attenuation in similar designs where the louvers did not permit gas rotation in only one direction.

FIGS. 5 7 illustrate a muffler 101 which is similar to the muffler of FIG. 4 but which contains a tuning chamber for attenuating a predetermined relatively low troublesome frequency. The muffler 101 is preferably formed of low carbon steel and has an outer shell 103 with a reduced diameter inlet portion 105 at one end and a reduced diameter outlet portion 107 at the other end. An inlet bushing 109 is secured in portion 105 and may be slotted at 111 to facilitate clamping to an exhaust gas conduit (not shown). A curved outlet spout 113 is secured in portion 107 to serve as the outlet end on an exhaust system and an outlet bushing 115 is also secured in the portion 107. The bushings 109 and 115 have reduced diameter inner end portions which receive and support the open opposite ends of axially aligned inlet and outlet gas flow tubes 117 and 119, respectively. The inner ends of the tubes 117 and 119 are supported in the ends of a connecting flow tube 121 to provide a continuous tubular gas flow passage means whereby gas flows straight through the muffler from one end to the other. The connector tube 121 has a reduced diameter portion 123 (corresponding to portion 19 of FIG. 4) that is preferably provided by pinching the sidewall as indicated by pinches 125. The various parts are preferably secured together by spotwelds (indicated in the drawings by xs) and it will be seen that the bushing 115 is preferably free to shift axially inside of portion 107.

The inlet flow tube 117 has an inlet louver patch 127 opening into the chamber 129 formed by shell 103 around the combined tubes 117, 119, and 121; and the outlet flow tube 119 has an outlet louver patch 131 opening into chamber 129. The louvers 133 in the patches 127 and 131 are preferably shaped and arranged as described above in connection with muffler 1.

Thus, as seen in FIG. 6, the louvers in patch 127 face in one direction (counterclockwise) and, as seen in FIG. 7, the louvers in patch 131 face in the opposite direction (clockwise) whereby the gas forced into chamber 129 can flow into and out ofit while rotating in only one direction.

The inlet tube 117 is provided with a second louver patch 135 which connects the inside of the tube to the upstream end of a long annular chamber 137 surrounding inner portions of the tubes 117 and 119 and the tube 121, the chamber being defined by an inner shell 139. The shell 139 is supported on tubes 117 and 119 by its reduced ends as provided by pinches 141 which close the ends of the shell and clamp them to the tubes. The chamber 137 extends over a major part of the length of the shell 103 and its length in combination with the opening provided by louver patch 135 enables it to be tuned to attenuate a relatively low frequency that may be otherwise troublesome in the exhaust system. The chamber, for example, may have a length between the axial midpoint of patch 135 and the downstream end of the chamber which is substantially equal to a quarter wave length of the frequency to be attenuated.

Modifications in the specific structures shown may be made without departing from the spirit and scope of the invention.

I claim:

1. A muffler for attenuating sound in flowing gas comprising an outer shell having an inlet at one end and an outlet at the outer end, a tubular gas flow member within said shell and connected to said inlet and outlet, the space between said member and shell forming a gas flow chamber, said tubular member containing a flow obstructing means at a central portion thereof, said tubular member having a first patch of louvers located on the inlet side of said obstructing means and a second patch of louvers located on the outlet side of said obstructing means, said chamber extending between and connecting said louver patches, the louvers in each of said patches opening on the exterior of the tubular member and all the openings in each patch facing in one tangential direction with respect to the length of the tubular member, all the louvers in the first patch facing in the opposite tangential direction to all the louvers in the second patch to provide gas flow directing means for rotating the gas in substantially one direction only as it flows into and out of said chamber and as it moves longitudinally through the chamber from the first patch of louvers to the second patch of louvers.

2. A muffler as set forth in claim 1 wherein said obstructing means comprises an imperforate partition whereby all gas flows through said gas flow chamber.

3. A muffler as set forth in claim 1 wherein said obstructung means comprises a reduced diameter cross sectional area whereby a portion of the gas flows through said gas flow chamber.

4. A muffler as set forth in claim 1 wherein said tubular member comprises a straight open ended tube connected at one end to said inlet and at the other end to the outlet.

5. A muffler as set forth in claim 4 wherein said obstructing means comprises an imperforate partition in said tube.

6. A muffler as set forth in claim 4 wherein said obstructing means comprises a reduced diameter portion insaidtube. 

1. A muffler for attenuating sound in flowing gas comprising an outer shell having an inlet at one end and an outlet at the outer end, a tubular gas flow member within said shell and connected to said inlet and outlet, the space between said membEr and shell forming a gas flow chamber, said tubular member containing a flow obstructing means at a central portion thereof, said tubular member having a first patch of louvers located on the inlet side of said obstructing means and a second patch of louvers located on the outlet side of said obstructing means, said chamber extending between and connecting said louver patches, the louvers in each of said patches opening on the exterior of the tubular member and all the openings in each patch facing in one tangential direction with respect to the length of the tubular member, all the louvers in the first patch facing in the opposite tangential direction to all the louvers in the second patch to provide gas flow directing means for rotating the gas in substantially one direction only as it flows into and out of said chamber and as it moves longitudinally through the chamber from the first patch of louvers to the second patch of louvers.
 2. A muffler as set forth in claim 1 wherein said obstructing means comprises an imperforate partition whereby all gas flows through said gas flow chamber.
 3. A muffler as set forth in claim 1 wherein said obstructung means comprises a reduced diameter cross sectional area whereby a portion of the gas flows through said gas flow chamber.
 4. A muffler as set forth in claim 1 wherein said tubular member comprises a straight open ended tube connected at one end to said inlet and at the other end to the outlet.
 5. A muffler as set forth in claim 4 wherein said obstructing means comprises an imperforate partition in said tube.
 6. A muffler as set forth in claim 4 wherein said obstructing means comprises a reduced diameter portion in said tube. 